[Herpetology • 2015] Isanophisgen. nov. • On the Taxonomic Status of the Thai Endemic Freshwater Snake Parahelicops boonsongi, with the Erection of A New Genus (Squamata: Natricidae)

Parahelicops boonsongi Taylor & Elbel, 1958 is known from only three specimens from Thailand. It has been placed either in the genus Parahelicops Bourret, 1934, along with Parahelicops annamensis Bourret, 1934, or in the genus Opisthotropis Günther, 1872. We compared its morphological characters with those of P. annamensis and with three other relevant genera, Opisthotropis, Pararhabdophis Bourret, 1934, and ParatapinophisAngel, 1929. Parahelicops boonsongi is phenotypically distinct from Parahelicops annamensis, Opisthotropis, and all other natricine genera. We consequently erect a new genus,Isanophis gen. nov., to accommodate Parahelicops boonsongi.

Etymology. The generic nomen Isanophis is derived from the word “Isan”, the Thai name of the north-eastern region of Thailand, and from the Greek word ophis, meaning “snake”. It describes the limited known range of this genus. This generic nomen is masculine in gender.